A colleague told us she ran into "three dudes in very distinct clothing" Monday night on Vermont Avenue, one with "a large black hat and crazy black hair" whom she pegged as Jack White from the White Stripes. Unlikely, we thought, because none of his bands (Stripes, the Raconteurs or the Dead Weather) were in D.C. this week.

Turns out it was White. And guess why? Because he's a space geek!

The guitarist-songwriter was on Capitol Hill for the Planetary Society's celebration of Carl Sagan on what would have been the late astronomer's 75th birthday. White is a huge fan of Sagan, who died in 1996. He told Sagan's widow and collaborator, Ann Druyan, that the Dead Weather's European tour bus had a Sagan room where the band watched old episodes of "Cosmos."

In September, he discovered "A Glorious Dawn," a trippy YouTube mash-up of Sagan video clips put to music (with a Stephen Hawking cameo) by composer John Boswell. White approached Boswell and Druyan about releasing it as a single on his Third Man Records label; they jumped at the chance to further popularize the video, which already has more than a million hits.

"I thought it was a brilliant hymn to reality," Druyan told us. "For me, science is just as spiritual as any organized form of religion. It's just that we don't have any good music." White, she said, is a perfect partner: "He's obviously a brilliant guy."

The single came out Monday in Nashville (and is out on iTunes next week), but White celebrated in D.C. with Druyan, "Nova" astrophysicist Neil deGrasse Tyson,Bill Nye the Science Guy and Al Gore (via video). "Not your usual group for a Jack White event," said Planetary Society co-founder Lou Friedman.

Late Monday, White became the group's newest member. Said Friedman: "He said he's highly motivated to keep in touch, so we're very excited."